Control of the preparation conditions is used to enhance the performance of sol-gel derived carbon composite enzyme electrodes. In particular, changes in the water content during the acid-catalyzed hydrolysis strongly affect the macroporosity of the resulting biogel network. Hence, while for the low-water process the response is controlled by the enzyme kinetics, high-water preparations lead to mass-transport restrictions. Such diffusional limitations within the electrode interior result in an extended linear dynamic range (without the need for external membranes). Scanning electron microscopy provides images of biogel microstructures, accrued from the use of different water contents. The ceramic-carbon biosensors offer improved retention of artificial electron accepters compared to conventional carbon composite bioelectrodes. The silica-containing surface also displays an intrinsic electrocatalytic hydrogen peroxide response, and hence offers a low-potential monitoring of the glucose substrate.